Production of paraffin fuels using renewable materials by a continuous hydrotreatment comprising a pre-treatment step

ABSTRACT

A process for hydrotreatment of a feed from renewable sources such as vegetable oils for the production of paraffinic hydrocarbons comprising pre-treatment by crystallisation and/or precipitation allowing the elimination of insoluble inorganic impurities under hydrotreatment conditions. The flow of the total feed is divided up into a certain number of different, part flows equal to the number of catalytic zones in the reactor, and the different part flows are injected in the successive catalytic zones in increasing proportions to produce an effluent containing paraffinic hydrocarbons.

The invention relates to a process for the production of paraffinichydrocarbons that can be used as fuels by hydrotreatment of feeds fromrenewable sources such as oils and fats of vegetable or animal origin.In particular, the invention relates to a process for the production ofparaffinic hydrocarbons by hydrotreatment of feeds from renewablesources, in which a thorough pre-treatment step, allowing theelimination of the inorganic impurities contained in said feeds, isincorporated upstream of the fixed bed hydrotreatment catalytic zones.

The present international context is characterised primarily by therapid growth in the need for fuels, in particular those with gas oil andkerosene bases, and also by the scale of the problems associated withglobal warming and emissions of greenhouse gases. The result is a desireto reduce energy dependence upon raw materials of fossil origin and areduction in CO₂ emissions. In this context, the search for new feedsfrom renewable sources represents a major challenge of increasingimportance. Examples of such feeds include vegetable oils (of food- ornon-food-grade) or those from algae and animals fats.

Such feeds are mainly comprised of triglycerides and free fatty acids,such molecules comprising hydrocarbon chains of fatty acids with anumber of carbon atoms of between 4 and 24, and a number of unsaturatedbonds generally of between 0 and 3, with higher levels for algae oilsfor example.

The very high molecular weight (>600 g/mol) of the triglycerides and thehigh viscosity of the feeds concerned means that use of these bothdirectly or in a mixture in fuel bases presents difficulties for modernengines. However, the hydrocarbon chains constituting the triglyceridesare essentially linear and their length (number of carbon atoms) iscompatible with the hydrocarbons present in fuel bases.

It is thus necessary to convert such feeds to obtain fuel bases(including diesel and kerosene) of high quality that in particular areup to specification either directly or following mixing with otherfractions from crude oil. Diesel must meet specification EN590 andkerosene must meet the requirements described in the International AirTransport Association (IATA) Guidance Material for Aviation Turbine FuelSpecifications based on ASTM D1655.

One possible approach is the catalytic conversion of triglycerides intodeoxygenated paraffinic fuel in the presence of hydrogen(hydrotreatment).

During hydrotreatment the reactions which the feed containing thetriglycerides undergoes are as follows:

-   -   the hydrogenation reaction of the unsaturated bonds of the        hydrocarbon chains of the fatty acids of triglycerides and        esters;    -   the deoxygenation reactions via the following two reaction        pathways:        -   hydrodeoxygenation (HDO) leading to the formation of water            by consumption of hydrogen and the formation of hydrocarbons            with a carbon number (C_(n)) equal to that of the initial            fatty acid chains;        -   decarboxylation/decarbonylation leading to the formation of            carbon oxides (carbon monoxide and dioxide: CO and CO₂) and            the formation of hydrocarbons containing one less carbon            (C_(.)) than the initial fatty acid chains;    -   the hydrodenitrogenation (HDN) reactions, the term used to        denote the reactions that allow removal of the nitrogen from the        feed with the production of NH₃.

Hydrogenation of the unsaturated bonds of the hydrocarbon chains(carbon-carbon double bonds) is highly exothermic and the increase intemperature brought about by the release of heat can lead to temperaturelevels where the contribution of the decarboxylation reactions becomessignificant. The hydrodeoxygenation reactions, including thedecarboxylation reactions, are also exothermic reactions.Hydrodeoxygenation is generally favoured at a lower temperature overdecarboxylation/decarbonylation. The hydrodenitrogenation reactions aremore difficult and require higher temperatures than for hydrogenationand hydrodeoxygenation. Hydrodenitrogenation is generally necessarybecause the nitrogen compounds are generally inhibitors ofhydroisomerisation catalysts which are optionally used followinghydrotreatment. Hydroisomerisation allows an improvement in theproperties in the cold state of the fuel bases following hydrotreatment,in particular when the production of kerosene is envisaged.

As a consequence, strict temperature control in the hydrotreatmentsection is necessary as an excessive temperature brings with it thedisadvantages of favouring undesirable secondary reactions such aspolymerisation, cracking, coke deposits and deactivation of thecatalyst.

Furthermore, such feeds from renewable sources also contain significantquantities of impurities. These impurities can contain at least oneinorganic element. Said impurities containing at least one inorganicelement essentially comprise compounds containing phosphorous such asphospholipids which are emulsifying and surface-active agents whichhamper the refining operations and which belong to the family ofglyceridic compounds. Said impurities containing at least one inorganicelement can also comprise alkaline-earth elements such as phospatidicacid salts or also metals, alkali metals, chlorophylls or transitionelements in various forms.

Complex and polar phospholipids are amphiphilic molecules having onelipophilic apolar “head” comprising two fatty acids and one hydrophilicpolar “head” based on the pairing of a phosphoric acid and a function ofvariable kind (amino-alcohol, polyol, etc). These impurities can also beorganic. Said organic impurities essentially comprise nitrogen such assphingolipids and various non-chelated chlorophylls.

In fact, said impurities containing at least one inorganic element,contained in said feeds are miscible in oil under hydrotreatmentconditions. During the conversion of the triglycerides and/or fattyacids into paraffinic hydrocarbons, said impurities decompose and thentheir inorganic residues combine to form non-miscible salts whichprecipitate for example in the form of mixed phosphates of calciumand/or of magnesium of the type Ca_(x)Mg_(y)(PO₄)_(z), which areinsoluble in the reaction medium. The precipitation of these saltscauses an accumulation of inorganic solids in the catalytic bed andconsequently an increase in the loss of pressure in the reactor,clogging of the catalytic bed and deactivation of the hydrotreatmentcatalyst through clogging of the pores. The cycle time is reduced by thepresence of these impurities.

Moreover, the organic nitrogen impurities and the nitrogen impuritiescontaining at least one inorganic element present in said feed are nottotally eliminated during the hydrotreatment step. The result is a lossof performance of the optional hydroisomerisation step downstream.

The object of this invention is to address these disadvantages.

One object of this invention is to provide a hydrotreatment process forrenewable feeds, allowing the promotion primarily of hydrodeoxygenationreactions by the formation of water while at the same time allowing:

-   -   efficient performance, by this same process, of the        hydrodenitrogenation necessary to preserve the catalytic        activity of the optional hydroisomerisation section and    -   limitation of the clogging of the catalytic bed(s) containing        the hydrotreatment catalyst, deactivation of said catalyst and        thus the loss of pressure associated with the accumulation of        inorganic solids in the catalytic bed(s) through the use        upstream of said catalytic beds, of a specific pre-treatment        step allowing elimination of the inorganic impurities present in        said feed.

Another object of this invention is to provide a hydrotreatment processfor renewable feeds allowing the promotion primarily ofhydrodeoxygenation reactions and thus maximisation of thehydrodeoxygenation yield whilst increasing the useful life of thecatalytic hydrotreatment system through the elimination of the insolublecaking species.

Prior Art

Numerous documents from the prior art propose processes for thehydrotreatment of renewable feeds using an optional pre-treatment stepupstream of the hydrotreatment.

Document US 2009/0318737 describes a process for producing fuels and inparticular gas oil originating from renewable starting materials such asoils and fats of vegetable and animal origin. The process consists oftreating a first portion of a renewable starting material byhydrogenation and deoxygenation in a first reaction zone and a secondportion of a renewable starting material by hydrogenation anddeoxygenation in a second reaction zone. A portion of the paraffinichydrocarbon product obtained is recycled to the first reaction zone toincrease the hydrogen solubility of the reaction mixture, using a ratiofor the recycle to the first portion of renewable starting materials inthe range 2 to 8 by volume (weight ratio in the range 1.7 to 6.9). Thefact that the quantity of hydrogen in the liquid phase is maximizedmeans that the degree of deactivation of the catalyst can be reduced,which means that the pressure can be reduced,decarboxylation/decarbonylation reactions can be promoted andhydrodeoxygenation reactions can be reduced, and thus the hydrogenconsumption is reduced. No information is given regarding the quantityof nitrogen in the starting materials and the paraffinic effluents. Thefeed resulting from renewable starting materials can advantageouslyundergo a pre-treatment step in order to eliminate contaminants such asfor example the alkali metals present in said feed. The pre-treatmentstep can consist of an ion exchange on a resin, acid washing, use ofguard beds with or without demetallisation catalyst or solventextraction and filtration.

Patent application EP 2 226 375 proposes a process for continuoushydrogenation of a feed originating from renewable sources containingtriglycerides in a fixed bed reactor system containing a plurality ofcatalytic beds disposed in series and comprising a hydrogenationcatalyst, using less recycle and as a result requiring limitedtransformation of existing units. The feed is introduced by stagedinjection so that the various catalytic beds receive more and more feedin the direction of flow. The recycled liquid is only added upstream ofthe first catalytic zone. This limitation to the quantity of productrecycled to the reactor means that the total flow rate in the reactor,and thus the hydraulic load down-stream of the reactor, can be limited.The preferred range for the total recycle for the fresh feed is lessthan 1, preferably less than 0.5 by weight. The ratio of diluent tofresh feed entering each catalytic bed is less than or equal to 4 byweight. The inlet temperature is identical for each bed.

Application EP 2 226 375 promotes the hydrodeoxygenation pathway byeliminating oxygen and forming water, rather than eliminating oxygen bydecarboxylation reactions by means of controlling the inlet temperaturesof the catalytic beds. Document EP 2 226 375 does not mention theproblem of the presence of inorganic contaminants in said feed.

Patent application US 2009/0266743 describes a process for treatment ofa feed containing triglycerides alone or in a mixture with ahydrocarbonated feed such as for example a middle distillate feed and inparticular a gas oil feed. The treatment process consists of a thermalpre-treatment of said feed at a temperature of between 40 and 540° C.,possibly in the presence of a gas such as hydrogen, nitrogen, helium,carbon monoxide and carbon dioxide, followed by a hydrotreatment toproduce a gas oil type fuel.

The Applicant has observed that the quantity of nitrogen in therenewable starting material may vary considerably as a function of theorigin of the material. In particular, the nitrogen content is generallyhigher in animal fats than in vegetable oils. Further, adjusting thetemperature in the various catalytic zones of the hydrotreatment reactorto levels which are as low as possible in order to promotehydrodeoxygenation reactions leading to the formation of water may causedifficulties in obtaining low nitrogen content levels in the paraffinicfuel produced after hydrotreatment. Thus, it is well known thathydrodenitrogenation reactions (HDN) are more difficult to carry outthan hydrodesulphurization reactions (HDS) or hydrodeoxygenationreactions (HDO), and as a result necessitate higher temperatures inorder to reach the same level. Too high a level of nitrogen compounds inthe paraffinic fuel produced by the hydrotreatment process results inpoorer performance for the optional downstream hydroisomerization.Hydroisomerization (HIS) may be advantageous in order to produce dieselwith improved cold flow properties and/or to produce kerosene satisfyingfreezing point specifications. In order to compensate for this effect,it would then be necessary to increase the severity of the HIS section,resulting in a lower yield for high value products such as diesel fueland kerosene, and a reduced cycle, and as a result, an increase inoperating costs.

The Applicant has thus implemented upstream of the catalytic bed(s)containing the hydrotreatment catalyst in such a way as to increase theuseful life of said hydrotreatment catalyst, a thorough pre-treatmentstep of this feed allowing the elimination of the inorganic contaminantswhich are insoluble under hydrotreatment conditions, present in saidfeed. This pre-treatment step also allows reinforced elimination of thenitrogen compounds present in said feed by adsorption of specificnitrogen compounds.

Object of the Invention

Thus the aim of this invention is, then, through a combination of theintroduction of the feeds in increasing proportions and a high recyclein the first zone and the implementation of a specific pre-treatmentstep using a portion of the recycle, to propose a hydrotreatment processfor renewable feeds simultaneously making it possible to:

-   -   allow the elimination of the inorganic impurities, insoluble        under hydrotreatment conditions, present in said feed,    -   promote primarily hydrodeoxygenation reactions by the formation        of water;    -   effectively perform by this same process the        hydrodenitrogenation necessary to preserve the catalytic        activity of the optional hydroisomerisation section;    -   reinforce the elimination of nitrogen compounds and    -   improve the useful life of the catalytic hydrotreatment system.

Thus, the present invention concerns a process for the hydrotreatment ofa feed originating from renewable sources in order to produce paraffinichydrocarbons in which hydrotreatment step c) is performed in thepresence of hydrogen in excess of the theoretical hydrogen consumptionand under hydrotreatment conditions in a fixed bed reactor having aplurality of catalytic zones disposed in series and comprising ahydrotreatment catalyst, characterized in that:

-   -   a) the total feed flow F0 is mixed with a flow RPP comprising at        least a portion of the liquid fraction R containing paraffinic        hydrocarbons from the separation step d), said mixture being        heated to a temperature of between 130 and 320° C.;    -   b) said mixture is introduced into a pre-treatment zone in which        the flow of said mixture takes place via a porous medium        consisting of a particle bed referred to as a solid bed, said        solid bed having a void fraction of between 0.25 and 0.8;    -   c) the effluent from the pre-treatment zone (F+εRPP), ε being        between 0 and 1, is divided into at least a certain number of        different part flows (F1+ε₁RPP) to (Fn+ε_(n)RPP) equal to the        number of catalytic zones n in the reactor, the first part flow        (F1+ε₁RPP) is injected into the first catalytic zone, the second        part flow (F2+ε₂RPP) is injected into the second catalytic zone        and so on, if n greater than 2, the sum of the ε_(i) being equal        to ε;        -   the various part flows are injected into successive            catalytic zones in increasing proportions such that F1/F is            less than or equal to F2/F, which itself is less than or            equal to F3/F and so on until F(n−1)/F is less than or equal            to Fn/F, in order to produce an effluent containing            paraffinic hydrocarbons;    -   d) said effluent containing paraffinic hydrocarbons is subjected        to at least one separation step allowing separation of at least        one gaseous fraction and at least one liquid fraction containing        the paraffinic hydrocarbons;    -   e) at least a portion R of said liquid fraction containing the        paraffinic hydrocarbons from step b) is divided into at least a        flow RLC and into said recycle flow RPP upstream of step a) and        mixed with the total feed flow F0 and said flow RLC is divided        into at least a certain number of different part flows R1-Rn        less than or equal to the number of catalytic zones n in the        reactor, said flows R1-Rn being recycled upstream of the        catalytic zones 1-n, so that the weight ratio between the flow        of paraffinic hydrocarbons (R1+ε₁RPP) sent to the first        catalytic zone and the part flow F1 of the feed introduced into        the first catalytic zone is greater than or equal to 10.

An advantage of the present invention is that it can be used to carryout hydrodenitrogenation and hydrodeoxygenation in the same catalyticzone without having recourse to a second, hydrodenitrogenation, reactordownstream. In fact, introducing the feed in increasing proportionscoupled with a large recycle to the first zone means that, by means ofan increasing temperature profile, a sufficiently hot zone can beobtained at the end of the catalytic zone to allow hydrodenitrogenationwhile keeping the temperature sufficiently low at the inlet to thecatalytic zone to promote the hydrodeoxygenation reactions. Furthermore,the pre-treatment step employed upstream using the catalytic bed(s)containing hydrotreatment catalysts also allows reinforced eliminationof the nitrogen compounds present in said feed by elimination of theimpurities and in particular of specific nitrogen compounds such asamino-alcohols of the phosphatidylcholine, phosphatidylethanolamine andphosphatydylserine type, and the sphingolipids and chlorophylls.

Another advantage of the invention is that it limits the deactivation ofsaid catalyst and the loss of pressure associated with the accumulationof inorganic solids in the catalytic bed(s) and thus the clogging of thecatalytic beds containing the hydrotreatment catalyst by the employmentupstream of said catalytic bed(s), said specific pre-treatment stepallowing elimination of the inorganic contaminants present in said feedby precipitation/crystallisation and/or hot adsorptions.

A further advantage of the present invention consists of promoting thehydrodeoxygenation pathway by eliminating oxygen and forming water,rather than eliminating oxygen by decarboxylation reactions, bycontrolling the temperatures to keep them adapted to hydrodeoxygenationat the inlet to each catalytic zone. The advantages of this solution arean increase in the yield of paraffinic hydrocarbons and a reduction inthe quantity of CO/CO₂ formed, which means that the inhibiting effect ofCO on the activity of the hydrotreatment catalyst can be limited.Promoting the hydrodeoxygenation pathway also means that corrosion dueto the presence of CO₂ in the reactor can be reduced.

A further advantage of the present invention is the limitation in thequantity of product recycled to the reactor, which allows the total flowin the reactor, and thus the hydraulic feed downstream of the reactor,to be limited.

Description

The process of the present invention consists of converting intoparaffinic hydrocarbons, more precisely into middle distillates(kerosenes and/or gas oils), a wide range of feeds of renewable origin,essentially composed of triglycerides and fatty acids. These feeds aregenerally characterized by a high molar mass (usually more than 800g/mole); the chains of the fatty acids of which they are composedcontain in the range 4 to 24 carbon atoms, and generally in the range 0to 3 unsaturated bonds per chain, with higher values possibly beingobtained for certain specific feeds. Non-exhaustive examples of feedswhich may be converted by the process of the present invention which maybe cited are: vegetable oils such as rapeseed, jatropha, soya, palmkernel, sunflower, olive, coprah and camelina oils, fish oils orheterotrophic or autotrophic algal oils or animal fats such as beefsuet, or residues from the paper industry (for example tall oil) ormixtures of these various feeds.

Preferably, the feeds derived from renewable sources are selected fromoils and fats of vegetable or animal origin or mixtures of such feeds,containing triglycerides and/or free fatty acids and/or esters.

All of these feeds have high oxygen contents, and also significantquantities of impurities, in very variable quantities depending on theorigin of the feeds, which may contain at least one inorganic element,and organic impurities contain essentially nitrogen as described above.Said feeds can generally have a content of inorganic compounds ofbetween 0.1 and 2500 ppm. The quantities of nitrogen and sulphur aregenerally in the range 1 ppm to 100 ppm by weight approximately,preferably less than 100 ppm, depending on their nature. They may reachup to 1% by weight for particular feeds.

The feeds from renewable sources that are used in the process accordingto the invention can advantageously be in raw form, or may haveundergone a refining step for edible oils known to a person skilled inthe art such as for example a degumming or dephosphatation. Said feedsthat have undergone at least said refining step are referred to assemi-refined and at the end of this treatment still contain up to 20 ppmof phosphorous, calcium, magnesium, iron and/or zinc, in the form ofphospholipids.

The invention will now be described with reference to the figures inorder to facilitate comprehension; the figures do not limit the generalnature of the invention.

Pre-Treatment

The feed in raw state or possibly having undergone at least one refiningstep, also termed total fresh feed F0, is injected into the line (0)shown in FIG. 1.

According to step a) of the process according to the invention, the flowof total fresh feed F0 is mixed with a flow RPP constituted by at leasta portion of the recycled liquid fraction R containing paraffinichydrocarbons from separation step d).

In fact, according to the invention, at least a portion R of the liquidfraction containing the paraffinic hydrocarbons produced by thetreatment process according to the invention and resulting fromseparation step d) is recycled and divided into at least a flow RLC,which is recycled upstream of the catalytic zones according to step e)of the process according to the invention and a flow RPP constituted byat least a portion of the liquid fraction R containing paraffinichydrocarbons, recycled upstream of the pre-treatment zone.

The flow of the total fresh feed F0 is preferably mixed with said flowRPP in a device allowing two flows to come into contact and homogenousmixing of these flows.

In accordance with the invention, the mixture of the total fresh feed F0and of said flow RPP is heated to a temperature of between 130 and 320°C., preferably of between 160 and 250° C. and most preferably between160 and 220° C. Said mixture can advantageously be heated by thecontribution of heat from the RPP flow. In the event that the heatcontributed by the RPP flow is insufficient, said mixture isadvantageously heated by any of the means known to a person skilled inthe art such as for example passing through a heat exchanger, or anoven.

The proportion of the flow RPP introduced in step a) of the processaccording to the invention in relation to the total fresh feed flow F0is such that the mass flow ratio RPP/F0 is advantageously of between 0.1and 5, preferably between 0.5 and 3 and most preferably between 1 and 3.

According to step b) of the process according to the invention, saidmixture is introduced, via the line (1) into a pre-treatment zone F-01shown in the Figure, in which the flow of the mixture takes placethrough a porous medium consisting of a bed of particles termed a fixedbed, said fixed bed having a void fraction of between 0.25 and 0.8.

The particles that make up the bed preferably comprise materials with aspecific surface of between 0.5 and 320 m²/g.

The materials that make up the particles of the bed are preferablyselected from among the porous refractory oxides, advantageouslyselected from among alumina, silica, activated alumina, silica-aluminas,metal oxides and non-metal oxides. Said materials can advantageouslyalso be selected from among the oxide ceramics, the non-oxide ceramicsor the composite ceramics or materials such as silicon carbides,activated carbons, calcium aluminates, metals and graphite. In a highlypreferred manner, said material is selected from among the porousrefractory oxides.

In an even more preferable manner, said mixture is introduced into apre-treatment zone in which the mixture flows through at least one fixedbed of particles of a porous refractory oxide free from catalytic metalsselected from groups 6 and 8 to 12.

Said particles of the fixed bed used in the pre-treatment zone accordingto the present invention can advantageously be shaped and preferably inthe form of spherical particles or oblong, cylindrical, hollow or solid,twisted cylinders, multilobes, for example with a number of lobes ofbetween 2 and 5, or ring-shaped extrudates. Said particles arepreferably in the form of spherical or extruded particles with adiameter of between 0.5 and 20 mm and preferably of between 0.5 and 10mm.

Said particles of the fixed bed can advantageously have more specificgeometrical forms in order to increase their void fraction. Saidparticles of the fixed bed can also advantageously have the followingforms: hollow cylinders, hollow rings, Rashig rings, toothed hollowcylinders, crenelated hollow cylinders, cartwheels, Blend saddles, ormultiple-hole cylinders.

Their external diameter advantageously varies between 1 and 35 mm.

Said particles of the fixed bed can advantageously be used alone or in amixture.

It is particularly advantageous to superimpose different materials in atleast two different fixed beds of varying height. It is alsoparticularly advantageous to superimpose particles of different forms,the particles forming the fixed bed having the greatest void fractionbeing preferably used in the first fixed bed(s), at the inlet to thepre-treatment zone.

Where said materials are porous refractory oxides, the preferred porousrefractory oxides have a macroporosity.

Said porous refractory oxides preferably have a macroporous volume,measured by mercury intrusion, that is to say a volume of pores whoseaverage diameter is greater than 500 A, of more than 0.1 ml/g, andpreferably of between 0.125 and 0.4 ml/g. Said porous refractory oxidesalso advantageously have a total porous volume of more than 0.60 ml/g,and preferably of between 0.625 and 1.5 ml/g and a specific surfaceexpressed in S_(BET) of advantageously between 30 m2/g and 320 m2/g.

During said pre-treatment step, of the raw or semi-refined feed,following heating of the mixture of the flow of total fresh feed F0 withsaid flow RPP under good conditions in terms of temperature, thedecomposition is noted of the impurities containing at least oneinorganic element then the recombination of their inorganic residues toform non-miscible salts which precipitate and are insoluble in thereaction medium. This precipitation is promoted because the impuritiesof a polar nature are less miscible in the feed/oil mixture with RPPparaffins added than in the oil alone. Concentrated at the interfacesbetween the oil-rich phase and the paraffin-rich phase and in contactwith the porous medium of the pre-treatment step, preferably consistingof solids with a large contact area, the inorganic impuritiesprecipitate at the surface of these. This solid precipitate which isnon-miscible in the reaction medium deposits on the porous medium, againtermed guard bed having the feature that said guard bed is used with aminimum activation temperature of the thermal crystallisation and/orprecipitation reaction sought.

Said pre-treatment step, carried out upstream of the catalytic bed(s)containing the hydrotreatment catalysts thus allows the elimination ofthe inorganic impurities present in the feed.

Moreover, said pre-treatment step also allows the reinforcement of theelimination of the nitrogen compounds present in said feed and inparticular the organic nitrogen impurities and the nitrogen impuritiescontaining at least one inorganic element such as the amino-alcohols ofthe phosphatidylcholine, phosphatidylethanolamine or phosphatydylserinetype, and the sphingolipids and chlorophylls. In fact, the presence ofthe porosity associated with the nature of the solid employed in thepre-treatment step, or the nature of the solids resulting from thecrystallisation or precipitation of the inorganic impurities, alsoallows the adsorption of the nitrogen impurities such as thesphingolipids or the chlorophylls or any other residual nitrogencompound.

Said pre-treatment step b) preferably takes place in the absence ofhydrogen.

Pre-treatment step b) preferably comprises in addition to thepre-treatment zone, a separation zone. In the case that saidpre-treatment step d) comprises a separation zone, the effluent from thepre-treatment zone (F+εRPP) with ε of between 0 and 1 is then possiblyintroduced, via line (2) into a separation zone, B-01 shown in FIG. 1,in such a way as to separate a paraffin-rich effluent (1-ε) RPP. ε ispreferably between 0.01 and 0.5.

Said paraffin-rich effluent (1-ε) RPP, preferably comprising at least90% by weight of paraffins is advantageously separated. Said effluent(1-ε) RPP is either advantageously re-injected with the flow RLC in thecatalytic zones according to case ii) shown in FIG. 1, or recycledupstream of the pre-treatment zone in a mixture with the RPP flowaccording to case iii) or sent back towards the flow of paraffinsleaving the unit according to case i).

ε represents the fraction of the paraffinic flow RPP entrained with thefeed F at the end of pre-treatment step b).

According to step c) of the process according to the invention, theeffluent from the pre-treatment zone (F+εRPP) which may have undergone astep for separation of a paraffin-rich effluent, is divided into atleast a certain number of different part flows (F1+ε₁RPP) to(Fn+ε_(n)RPP) equal to the number of catalytic zones n in the reactor,and the first part flow (F1+ε₁RPP) is injected into the first catalyticzone, the second part flow (F2+ε₂RPP) is injected into the secondcatalytic zone and so on, if n is greater than 2. The various part flowsare injected into successive catalytic zones in increasing proportionssuch that F1/F is less than or equal to F2/F, which itself is less thanor equal to F3/F and so on until F(n−1)/F is less than or equal to Fn/F,in order to produce an effluent containing paraffinic hydrocarbons.

The triglyceride-rich effluent (F+εRPP) coming from the pre-treatmentzone is mixed via line (3) with a hydrogen-rich gas (4). Saidhydrogen-rich gas can also contain other inert hydrocarbon compounds,that is to say which do not react as such with the constituents of thefeed. The hydrogen can advantageously come from additional hydrogenand/or the recycling of the hydrogen-rich gas from the separation stepemployed downstream of the hydrotreatment step. In practice the addedhydrogen can come from the steam reforming or from the conventionalcatalytic reforming possibly with added hydrogen from the steamreforming and light gases from separation step d), and its hydrogenpurity is advantageously between 75 and 95% by volume, the other gasespresent generally being methane, ethane, propane and butane. Thehydrogen-rich gas from the separation step employed downstream of thehydrotreatment step or also from the separation step employed after theoptional hydroisomerisation step, preferably first undergoes one or moreintermediate purification treatments before being recycled in thehydrotreatment and/or hydroisomerisation process.

According to one characteristic of the invention, the hydrogen used isin excess of the theoretical consumption, with the excess hydrogenrepresenting at least 50% of this theoretical consumption, preferablybetween 75 and 400%, and more preferably between 100% and 300%, 150%being a typical value. The quantity of hydrogen used is controlled bythe partial pressure of hydrogen.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 represents a schematic of an embodiment of the invention.

The following definitions will now be given, to provide a betterunderstanding of the present invention. They make reference to FIG. 1.The reactor comprises “n” catalytic zones. All of the flows areexpressed as the flow rate by weight.

-   -   F0: total flow of the renewable feed treated in the process    -   F+εRPP: effluent from the pre-treatment zone    -   F1+ε₁RPP+R1: part flow of the feed and part flow of recycle        introduced into the first catalytic zone Z1    -   F2+ε₂RPP+R2: part flow of the feed and part flow of recycle        introduced into the second catalytic zone Z2    -   F3+ε₃RPP+R3: part flow of the feed and part flow of recycle        introduced into the third catalytic zone Z3 and so on . . .    -   Fn+ε_(n)RPP+Rn: part flow of the feed and part flow of recycle        Rn introduced into the final catalytic zone Zn    -   R: total flow of recycle: recycled liquid fraction containing        the paraffinic hydrocarbons from separation step d). R is        divided into a flow RLC and a flow RPP.    -   RLC: recycle flow to the catalytic zone, constituted by at least        a portion of the recycled liquid fraction R containing        paraffinic hydrocarbons, recycled in at least the first        catalytic zone Z1. RLC can be divided into various flows R1 to        Rn depending on the number of catalytic zones to which it is        sent.    -   RPP: flow constituted by at least a portion of the recycle        liquid fraction R containing paraffinic hydrocarbons, recycled        upstream of the pre-treatment zone.

The total recycle rate (RT) is defined as the weight ratio between thetotal flow of paraffins of the recycle sent to the catalytic zones Z1 toZn and the total flow of the renewable feed sent to the catalytic zonesZ1 to Zn after passing through pre-treatment zone (F):

In the configuration (case i), where (1-ε)RPP is returned towards thehydroisomerisation section:RT=(RLC+εRPP)/F

In the configurations (case ii) and (case iii), where (1-ε)RPP isreturned towards the hydrotreatment section:RT=(RLC+RPP)/F=R/F

The total recycle rate (RT) is preferably less than 1.0, and morepreferably less than 0.5, said flows being expressed as a flow rate byweight.

The local recycle rate towards the first catalytic zone (RF1) is definedas the weight ratio between the flow of paraffins of the recycle sent tothe first catalytic zone Z1 that is to say (R1+ε₁RPP) and the part flowof the feed introduced into the first catalytic zone 1 (F1):RF1=(R1+ε₁ RPP)/F1

Except during the process start-up phase, the diluting agent which isrecycled at the level of the pre-treatment zone and at the level of thehydrotreatment catalytic zones Z1-Zn is constituted by a portion of theliquid hydrocarbon product leaving the hydrotreatment section. In theremainder of the present description, this diluting agent recycled tothe inlet of at least one catalytic zone is also termed the totalrecycle flow R, and its delivery is denoted by R in the abovedefinitions. The hydrotreatment section of the process is designed tocompletely convert the treated feeds, and so the total recycle flow Rproduced is a flow of hydrocarbon which is free of oxygen, which meansthat its oxygen content is below the analytical detection limit and isessentially composed of paraffins. As a consequence, this total recycleflow is inert to hydrotreatment reactions and thus fulfils its role asdiluent for the feed, meaning that the temperature rise in the catalyticzones is limited due to the exothermic nature of the reactions occurringtherein. Nevertheless, for a given capacity, i.e. for a given mass flowrate of treated feed, denoted F0, the aim is to limit the quantity ofliquid recycle injected into the catalytic zones, denoted RLC, in orderto limit the total flow rate of the flow supplied to said catalyticzones. This means that hydrotreatment reactors with dimensionscomparable to those of the reactors for hydrotreatment of oil cuts suchas gas oils can be used (thereby limiting costs), that pressure dropscan be limited and that reactor choking phenomena can be avoided.Furthermore, the pre-treatment zone employed upstream of the catalyticbed(s) containing the hydrotreatment catalyst also uses a flow RPPconstituted by at least a portion of the liquid fraction R containingparaffinic hydrocarbons, inert, which allows acceleration of thephenomena by which inorganic impurities are eliminated by precipitationand/or adsorptions of the latter.

It has been discovered that it is advantageous to inject the feed intovarious catalytic zones (mass flow rate (F1+R1+ε₁RPP) injected into zoneZ1, F2+R2+ε₂RPP into zone Z2, etc.) making sure thereby that increasingproportions of the feed are injected into the successive catalyticzones. This can be expressed as the following relationship:

F1/F less than or equal to F2/F, in turn less than or equal to F3/F,etc., and more generally F(n-1)/F less than or equal to Fn/F, for thegeneral case in which n is the number of catalytic zones employed. Theadvantage of such a feed distribution in the various successivecatalytic zones resides in the fact that the outlet temperatures for thevarious catalytic zones follow a rising profile, which means thatsufficient temperatures can be obtained to reduce the residualquantities of nitrogen in the product leaving the various zones, noteliminated in the pre-treatment step, as much as possible, with the aimof retaining the catalytic activity of the downstream hydroisomerizationsection.

According to the invention, a flow R1 is recycled upstream of the firstcatalytic zone Z1 such that the weight ratio between the flow ofparaffins (R1+ε₁RPP) injected at the inlet to said first catalytic zoneZ1 and the part flow F1 of feed introduced into Z1, is greater than orequal to 10.0, said flows being expressed as the mass flow. This ratiois also termed the local recycle (RF1) and is defined above. The use ofsuch an arrangement of the flows of feed and of liquid recycle means:

-   -   firstly, that a homogeneous temperature can be obtained in the        entire section of the reactor at the outlet from zone Z1;    -   secondly, that a sufficient temperature can be obtained at the        outlet from zone Z1, meaning that hydrodenitrogenation reactions        can be triggered and residual quantities of nitrogen in the        liquid hydrocarbon produced at the outlet from zone Z1 can        therefore be reduced;    -   and that higher temperatures can be obtained at the outlet from        the catalytic zones following zone Z1 (zones Z2 to Zn), which        are sufficient to augment the nitrogen elimination percentages.

In fact, introducing the feed in increasing proportions coupled with alarge local recycle to the first zone means that, by using an increasingprofile of temperatures, a sufficiently hot zone is obtained at the endof the catalytic zone to allow hydrodenitrogenation while keeping thetemperature sufficiently low at the inlet to the catalytic zone topromote hydrodeoxygenation reactions. The local recycle ratio of 10 ormore means that relatively little feed is injected onto the first zone,thereby allowing the remainder of the feed to be injected into thesuccessive catalytic zones in greater and increasing proportions. Theincrease in the quantity of feed injected into the successive zonesmeans that an increasing profile of inlet and outlet temperatures can beobtained for the various zones.

The flows entering the second catalytic zone Z2 are thus as follows:

-   -   at least part of the feed with added paraffins from the        pre-treatment zone injected at the inlet of zone Z2 (F2+ε₂RPP),        such that the weight ratio F2/F is greater than the weight ratio        F1/F;    -   the recycle liquid R1 injected at the inlet of zone Z1, made up        almost exclusively of paraffinic hydrocarbons and having passed        through zone Z1;    -   the effluent formed by the conversion of the feed in zone Z1,        corresponding to the flow F1. The liquid hydrocarbons present in        this effluent are free of oxygen and are almost exclusively        paraffinic hydrocarbons;    -   possibly the recycle liquid R2, made up almost exclusively of        paraffinic hydrocarbons and constituted by at least a portion of        the flow of recycle to the catalytic zone RLC.

During start-up phases, a wide range of hydrocarbons may be injectedsuch as, for example, a light gas oil, until a sufficient quantity ofparaffinic product is available for recycling to the inlet of at leastone catalytic zone.

The feed is supplied via line (O), as seen in FIG. 1, while thehydrogen-rich gas is supplied via line (4). The feed is injected intothe pre-treatment zone in a mixture with the flow of paraffins RPP froma portion of the recycle flow R from a portion of the paraffins producedat the outlet of the hydrotreatment. The flow F+εRPP from thepre-treatment zone is distributed into various flows F1+ε₁RPP,

F2+ε₂RPP, . . . , Fn+ε₁RPP supplying the various successive catalyticzones. The hydrogen-rich gas (flow (4)) is distributed in the samenumber of flows H1, H2, Hn. The flow F1+ε₁RPP is mixed with the gas flow(H1), the flow F2+ε₂RPP is mixed with the gas flow (H₂), and so on tothe n^(th) catalytic zone.

The temperature of the flow at the outlet from pre-treatment F+εRPP canbe adjusted in order to reach a temperature of less than 180° C.,preferably of less than 120° C., and more preferably less than 80° C. Itmust be sufficient to allow a sufficient reduction in viscosity and thusadequate transfer from the storage tanks to the hydrotreatment reactionsection. In the same manner, the temperature of the hydrogen-rich gaswhich is mixed with the feed is as low as possible while beingcompatible with the operation of the process, since it is advantageousfor the process to mix the feed with the hydrogen at low temperature inorder to reduce the temperature by a quench effect applied tohydrocarbon products leaving the various catalytic zones. In practice,since the temperature rises when compressing hydrogen-rich gas, thehydrogen is frequently cooled after compression. Preferably, thetemperature of the hydrogen-rich gas is in the range 40° C. to 100° C.,for example 50° C.

The temperature of the flow injected into the inlet to the catalyticzone Z1, that is to say the effluent from the pre-treatment zone(F1+ε₁RPP) and of the recycle liquid R1 must be carefully regulated. Thetemperature of said flow injected at the inlet to the catalytic zone Z1is preferably a minimum of 180° C., preferably 200° C. This allows thereaction series to be triggered: reactions for eliminating oxygen inaccordance with a mechanism that results in the formation of water, orin accordance with a decarboxylation/decarbonylation mechanism resultingin the formation of CO₂ and CO, but also hydrodenitrogenation reactionsin at least a portion of said catalytic zone. This inlet temperature maybe adjusted as a function of the nature of the feed. Advantageously, thetemperature at the outlet from the zone Z1 is more than 250° C. Thevolume of the catalyst employed in said catalytic zone is adapted sothat the conversion, i.e. the degree of elimination of oxygen, iscomplete at the outlet from said zone Z1.

At the outlet from catalytic zone Z1, a second flow of feed F2+ε₂RPP isadded, which represents a larger proportion of feed than that injectedat the inlet to zone Z1. This flow of feed is added to the flow ofhydrogen—(H₂) rich gas, and possibly the liquid recycle R2 constitutedby at least a portion of the flow RLC which itself results from theliquid fraction R containing paraffinic hydrocarbons from the separationstep d). The mixture is injected into the reaction zone, where it ismixed with the effluent from zone Z1. This allows a lowering of thetemperature of the products formed at the outlet of zone Z1, and thetemperature at the inlet to zone Z2 is thus generally higher than thatat the inlet to zone Z1. The same categories of reaction occur in thezone Z2 and the zone Z1, with slightly faster kinetics in the zone Z2due to the higher mean temperature.

The same principle applies in the successive catalytic zones, with theflow of pre-treated feed (Fn+ε_(n)RPP) and possibly a flow of recycle Rnbeing added to the completely converted product formed in the previouscatalytic zones.

As the feed is transformed into paraffinic hydrocarbons in a catalyticzone, the temperature increases in the zone, since hydrogenation anddeoxygenation reactions are highly exothermic reactions. Thus, thetemperature is sufficiently high towards the outlet of a catalytic zoneto be able to carry out the hydrodenitrogenation reaction. Thetemperature at the outlet of at least one catalytic zone is preferablymore than 300° C., more preferably more than 320° C.

The ratios between the hydrogen flows added to each of said flows (F1),. . . , (Fn), and the feed mass flow rates (F1), . . . , (Fn) are of thesame order of magnitude for the series of catalytic zones, the ratiobetween the flow rate of hydrogen and the flow rate of feed being in therange 300 to 1500 Nm³/m³, preferably in the range 600 to 900 Nm³/m³.

Optionally, it is possible to inject a complementary liquid flow betweenthe catalytic zones if it is felt that there is a need to further dilutethe feed.

In a preferred variation, valves for regulating the part flows of feedand hydrogen may be controlled by the temperatures at the inlets andoutlets for the catalytic zones so as to adjust the feed part flow andhydrogen flow as well as the liquid recycle flow R1 to Rn duringoperation. In this manner, the desired temperature at the inlet to thecatalytic zones and in the catalytic zones is maintained. Similarly, thetemperature may be controlled by varying the temperature of the feed(F+ε RPP) following pre-treatment and/or of the hydrogen injected and/orof the recycle in the reactor system.

The hydrotreatment reactor for the process according to the inventionmay contain a variable number n of catalytic zones. n is preferablybetween 3 and 10, preferably between 3 and 6. The term “catalytic zone”means a catalytic bed. Each catalytic zone may comprise one or morelayers of catalysts, identical or different, optionally supplemented byinert layers. The catalytic zones may contain identical or differentcatalysts.

The type of catalyst used in the hydrotreatment section of this processis well known in the art.

Concerning active catalysts in the sulphide form, and treated unrefinedfeeds generally having limited sulphur contents (less than 100 ppm byweight in general, and usually less than 50 ppm by weight), it issufficient to add a sulphur-containing compound such asdimethyldisulphide (DMDS) to the set of feed flows; under thetemperature conditions in the hydrotreatment section, it decomposes intoH₂S and methane. This device means that the hydrotreatment catalystsused in the present process can be kept in their sulphide form and thussufficient catalytic activity can be maintained throughout the cycle.Recommended injected DMDS contents are in the range 10 to 50 ppm byweight of sulphur equivalent with respect to the feed. In practice,adding DMDS corresponding to 50 ppm by weight sulphur of equivalent withrespect to the feed is sufficient to retain the catalytic activitythroughout the cycle.

The catalysts used in the hydrotreatment section of the processaccording to the invention may be an association of the catalystsdescribed below.

The hydrotreatment catalyst is a sulphurized catalyst which comprisesone or more elements from groups 6, 8, 9 and 10 of the periodic table ofthe elements, preferably nickel, molybdenum, tungsten and/or cobalt.

The hydrotreatment catalyst, preferably used in a fixed bed, isadvantageously a hydrotreatment catalyst comprising ahydro-dehydrogenating function comprising at least one metal from groupVIII and/or group VIB, used alone or as a mixture, and a supportselected from the group formed by alumina, silica, silica-aluminas,magnesia, clays and mixtures of at least two of these minerals. Saidsupport may also advantageously include other compounds, for exampleoxides selected from the group formed by boron oxide, zirconia, titaniumoxide and phosphoric anhydride. The preferred support is an aluminasupport, highly preferably η, δ or γ alumina.

Said catalyst is advantageously a catalyst comprising metals from groupVIII, preferably selected from nickel and cobalt, used alone or as amixture, preferably in association with at least one metal from groupVIB, preferably selected from molybdenum and tungsten, used alone or asa mixture. Preferably, a NiMo type catalyst is used.

The quantity of oxides of metals from group VIII, preferably nickeloxide, is advantageously in the range 0.5% to 10% by weight of nickeloxide (NiO), preferably in the range 1% to 5% by weight of nickel oxide,and the quantity of oxides of metals from group VIB, preferablymolybdenum trioxide, is advantageously in the range 1% to 30% by weightof molybdenum oxide (MoO₃), preferably 5% to 25% by weight, thepercentages being expressed as a % by weight with respect to the totalcatalyst mass.

The total quantity of oxides of metals from groups VIB and VIII in thecatalyst used is advantageously in the range 5% to 40% by weight,preferably in the range 6% to 30% by weight with respect to the totalcatalyst mass.

The weight ratio, expressed as the metal oxide, of the metal (or metals)from group VIB to the metal (or metals) from group VIII isadvantageously in the range 20 to 1, preferably in the range 10 to 2.

Said catalyst used in the hydrotreatment step of the process accordingto the invention must advantageously be characterized by a stronghydrogenating power in order to orientate the selectivity of thereaction as far as possible towards a hydrogenation which maintains thenumber of carbon atoms of the fatty chains, i.e. the hydrodeoxygenationpathway, in order to maximize the yield of hydrocarbons in the gas oiland/or kerosene distillation range. For this reason, it is preferable tooperate at a relatively low temperature. Maximizing the hydrogenatingfunction also means that polymerization and/or condensation reactionsleading to the formation of coke, which would degrade the stability ofthe catalytic performances, are limited.

Said catalyst used in the hydrotreatment step of the process accordingto the invention may also advantageously contain a doping elementselected from phosphorus and boron, used alone or as a mixture. Saiddoping element may be introduced into the matrix or, as is preferable,be deposited on the support. It is also possible to deposit silicon ontothe support, alone or with phosphorus and/or boron and/or fluorine.

The quantity by weight of the oxide of said doping element isadvantageously less than 20%, preferably less than 10%, and it isadvantageously at least 0.001% with respect to the total catalyst mass.

In a preferred variation, the catalysts used are like those described inpatent application FR 2 943 071, describing catalysts with highselectivity for hydrodeoxygenation reactions.

According to another preferred variation, use is made of the catalystsas described in patent application EP 2 210 663 which deals withsupported or bulk catalysts comprising an active phase consisting of aGroup VIB sulphide, in which the Group VIB element is molybdenum.

The context of the present invention also encompasses the use, in thehydrotreatment step of the process according to the invention,simultaneously or successively, of a single catalyst or a plurality ofdifferent catalysts in the catalytic zones.

In the context of the invention, it is thus possible to maintain anoverall conversion of the feed originating from a renewable source, i.e.a conversion by hydrodeoxygenation and decarboxylation/decarbonylationtogether, which is advantageously 90% or more; preferably, the overallconversion of the feed is equal to 100%, while maximizing the yield ofhydrodeoxygenation product or the conversion by hydrodeoxygenationwhich, in accordance with the invention, remains at 50% or higher. Inthe case in which catalysts with a high selectivity for HDO (asdescribed above) are used, the conversion by hydrodeoxygenation is 90%or higher, preferably 95% or higher and more preferably 96% or higher.In this case, the conversion by decarboxylation/decarbonylation ordecomposition/decarbonylation product yield from the feed from renewablesources is advantageously limited to at most 10%, preferably limited toat most 5% and more preferably to at most 4%.

The hydrodeoxygenation reaction results in the formation of water byconsuming hydrogen and forming hydrocarbons with the same number ofcarbon atoms as in the initial fatty acid chains. The effluent from thehydrodeoxygenation reactions comprises even-numbered hydrocarbons suchas C14 to C24 hydrocarbons and are vastly in the majority compared withthe odd-numbered hydrocarbons such as C15 to C23 obtained bydecarboxylation/decarbonylation reactions. The selectivity for thehydrodeoxygenation pathway is demonstrated by measuring the total yieldof hydrocarbons containing even numbers of carbon atoms and the totalyield of hydrocarbons containing an odd number of carbon atoms in theliquid fraction which can be upgraded to fuel. The yields of even andodd numbered hydrocarbons providing access to the reaction selectivity(HDO/decarboxylation/decarbonylation) are obtained by gaschromatographic analysis of the liquid effluents from the reaction whichcan be upgraded to fuel. The gas chromatographic analysis technique is amethod which is known to a person skilled in the art.

Unless otherwise indicated, the hydrotreatment process according to theinvention is operated under hydrotreatment conditions which aregenerally known in the art, such as those described in patent EP 1 741768. The total pressure is advantageously in the range 2 MPa to 15 MPa,and preferably in the range 5 MPa to 10 MPa.

According to the invention, the hydrogen is used in excess. In theprocess according to the invention, the ratio between the flow rate ofhydrogen and the flow rate of unrefined feed is advantageously in therange 300 to 1500 Nm³/m³, preferably in the range 600 to 900 Nm³/m³.

A satisfactory operation of the process according to the inventionresults in an overall HSV (defined as the ratio between the total volumeflow rate of the treated unrefined feed and the total volume of thecatalyst in the hydrotreatment section) advantageously in the range 0.1to 5.01 h⁻¹, preferably in the range 0.1 to 1.51 h⁻¹.

The temperatures used in the various zones of the hydrotreatment sectionhave to be carefully controlled in order to avoid, as far as possible,unwanted reactions such as:

-   -   feed polymerization reactions, which lead to the deposition of        coke and thus to deactivation of the catalyst;    -   decarboxylation/decarbonylation reactions, resulting in a loss        of middle distillate yield;        and at the same time to carry out total conversion of the feed        both as regards elimination of oxygen-containing compounds and        as regards elimination of nitrogen-containing compounds. In        general, the process according to the invention operates at a        temperature in the range 200° C. to 400° C. Introducing the feed        in increasing proportions coupled with a substantial recycle to        the first catalytic zone means that an increasing temperature        profile can be obtained at the inlet to the zones and also at        the outlet from the zones.

The temperature at the inlet to zone Z1 must preferably be more than180° C., preferably more than 200° C. The temperatures at the inlet tothe subsequent catalytic zones must be higher than that at the inlet tothe preceding zone, generally less than 300° C. and preferably less than280° C.

The temperature at the outlet from at least one catalytic zone ispreferably more than 300° C., preferably more than 320° C. Thetemperatures at the outlet from each of the catalytic zones mustpreferably be less than 400° C., more preferably less than 380° C., inorder to limit deactivation of the catalyst by coking.

The process according to the invention uses fixed trickle bed reactorswhich are known to a person skilled in the art. The reagents (feed andhydrogen) are introduced into the reactor as a descending co-currentflow from the top to the bottom of the reactor. Examples of suchreactors are described in the document U.S. Pat. No. 7,070,745.

Between each catalytic zone, it is possible to inject supplementalhydrogen in order to profit from a quench effect and to obtain thedesired temperatures at the inlet to the next catalytic zone. Thus,quench boxes may be installed between each catalytic zone in order toensure optimum temperature homogeneity over the whole section of thereactor, and for all of the catalytic zones.

In the same manner, distributors may be installed between each catalyticzone in order to guarantee a homogeneous supply of the liquid feed overthe whole section of the reactor, and for all of the catalytic zones.

One advantage of the process according to the invention consists in itsgreat flexibility depending on the origin of the feed. Feeds whichdiffer, in particular in the various degrees of unsaturation of thehydrocarbon chains, may be completely converted both as regards theelimination of oxygen (which leads to maximum efficiency of dilution ofthe unrefined feed in the next zone) and as regards the elimination ofnitrogen (which leads to better function of the downstreamhydroisomerization step).

Optionally, the process according to the invention may also convertfeeds from renewable sources mixed with oil cuts such as gas oils,kerosenes, or even gasolines from oil refining processes. Preferably,the oil cuts are oil feeds of the middle distillate type selected fromthe group formed by straight run gas oils and/or kerosenes and gas oilsand/or kerosenes from conversion processes, or any mixture thereof.

Preferably, the oil cuts are selected from the group formed by straightrun atmospheric gas oils, gas oils from conversion processes such asthose derived from coking, for example, from fixed bed hydroconversion(such as those from HYVAHL® processes which treat heavy feeds and wasdeveloped by the Applicant) or ebullated bed hydrotreatment processesfor heavy feeds (such as those derived from H-OIL® processes) or solventdeasphalted oils (for example using propane, butane or pentane) fromdeasphalting straight run vacuum distillation residue, or residuesderived from heavy feed conversion processes such as HYVAHL® or H-OIL®.The feeds may also advantageously be formed by mixing these variousfractions. They may also advantageously contain light gas oil orkerosene cuts with a distillation profile from approximately 100° C. toapproximately 370° C. They may also advantageously contain aromaticextracts and paraffins obtained in the context of the manufacture oflubricating oils.

In this case, the quantity of liquid recycle sent to the first catalyticzone of the hydrotreatment section may be greatly reduced or evendispensed with, since these flows of oil feeds then result from theirtreatment with hydrogen, with less heat being released than when feedsof renewable origin comprising substantial quantities of oxygen areused.

Separation

According to step d) of the process according to the invention, theeffluent containing paraffinic hydrocarbons from the final catalyticzone of step c) is subjected to at least one separation step allowingthe separation of at least a gaseous fraction and at least a liquidfraction containing the paraffinic hydrocarbons. The gaseous fractioncontains hydrogen, CO, CO₂, I′H₂S and light gases.

Said effluent containing paraffinic hydrocarbons from the finalcatalytic zone of step c) is drawn off in the line (5).

According to a first embodiment, separation step d) can be performed ina single step by a high-temperature, high-pressure separator (S) workingwithout pressure reduction at a temperature of between 145° C. and 280°C.

According to a second embodiment, not shown in FIG. 1, separation stepd) comprises a separation in two steps without pressure reduction, thefirst separation being carried out at between 145° C. and 280° C. in ahigh-temperature separator, and the second being carried out at between25° C. and 100° C. in a low-temperature separator not shown in theFigure. In a preferred embodiment, the condensate of the fractionobtained from the second separation step is introduced into a degassingreceptacle not shown in the Figure.

Preferably, said liquid fraction containing the paraffinic hydrocarbonsfrom gas/liquid separation step d) then undergoes a separation of atleast a portion, preferably all, of the remaining water which has beenformed during the hydrodeoxygenation reactions (not shown in theFigure).

The aim of this step is to separate water from the liquid containing theparaffinic hydrocarbons. The term “elimination of water” meanselimination of the water produced by the hydrodeoxygenation (HDO)reactions. The more or less complete elimination of water isadvantageously a function of the tolerance to water of thehydroisomerization catalyst used in the optional subsequent step of theprocess according to the invention. The water may be eliminated usingany method and technique which is known to a person skilled in the art,such as by drying, passage over a desiccant, flash, solvent extraction,distillation or decanting, for example, or by combining at least two ofthese methods.

Optionally, a final step for purification of the various pollutants maybe carried out using methods which are known to a person skilled in theart, such as by steam stripping or nitrogen stripping or by coalescenceand/or using a capture mass, for example.

According to step e) of the process according to the invention, at leastone portion R of said liquid fraction containing the paraffinichydrocarbons is divided into at least one flow RLC and into said recycleflow RPP upstream of step a) and mixed with the total feed flow F0 andsaid flow RLC is divided into at least a certain number of different,part flows R1 to Rn less than or equal to the number n of catalyticzones in the reactor, said flows R1 to Rn being recycled upstream of thecatalytic zones 1 to n, such that the weight ratio between the flow ofparaffinic hydrocarbons (R1+ε1RPP) sent into the first catalytic zoneand the part flow F1 of the feed introduced into the first catalyticzone is greater than or equal to 10.

The proportion of the flow RPP introduced in step a) of the processaccording to the invention in relation to the total recycle flow R issuch that the mass flow ratio RPP/R is advantageously of between 0.1 and0.9 and preferably between 0.15 and 0.8.

At least another portion of the liquid fraction containing theparaffinic hydrocarbons from separation step d) is advantageously notrecycled.

The portion of the liquid fraction containing the paraffinichydrocarbons from separation step d) which is not recycled in at leastone catalytic zone or in a mixture with the flow of total fresh feed F0upstream of the pre-treatment step, is sent either directly to the gasoil pool, or directly to an optional hydroisomerisation (HIS) section(6), in order to produce high quality kerosene and/or gas oil bases andin particular kerosene bases with good cold properties. In fact, saidnon-recycled portion of the liquid fraction containing the paraffinichydrocarbons from separation step d) of the process according to theinvention is sufficiently denitrogenated to preserve the catalyticactivity of the hydroisomerisation section. A hydrodenitrogenationreactor between the hydrotreatment and the hydroisomerisation isunnecessary.

Hydroisomerisation

According to a preferred implementation, at least a portion of theliquid fraction containing the paraffinic hydrocarbons from separationstep d) and not recycled is hydroisomerised in the presence of ahydroisomerisation catalyst. The optional hydroisomerisation step isadvantageously implemented under the operating conditions and in thepresence of hydroisomerisation catalysts known to a person skilled inthe art. The operating conditions and the catalysts used in saidhydroisomerisation step are preferably those described in patent FR 2943 071.

The hydroisomerised effluent then advantageously undergoes at least inpart, and preferably in full, one or more separations.

Said separation step(s) can advantageously comprise flash separation toseparate the gas from the liquid and/or atmospheric distillation.Preferably, the separation step(s) comprises (comprise) atmosphericdistillation. The aim of this step is to separate the gases from theliquid, and in particular to recover the hydrogen-rich gases which mayalso contain light compounds such as the C₁-C₄ cut, a gasoline cut (150°C.⁻) and at least one middle distillates cut (150° C.⁺) containingkerosene and/or gas oil. Upgrading the gasoline (or naphtha) cut is notthe aim of the present invention, but this cut may advantageously besent to a steam cracking unit for the production of hydrogen or forcatalytic reforming The hydrogen produced thereby may be injected intothe hydrotreatment and/or optional hydroisomerization step.

The middle distillates cut which represents the desired fuel bases maycomprise a cut containing gas oil and kerosene, or the two cuts may berecovered separately. These products are based on renewable sources anddo not contain sulphur-containing compounds.

At least a portion of the middle distillate cut or cuts mayadvantageously be recycled in a hydrotreatment step.

In a variation, at least a portion of the 150° C.⁺ cut may be recycledto the hydroisomerization step. This fraction thus undergoesisomerisation once again, meaning that cold properties of said fractioncan be improved.

In another variation, at least a portion of the 300° C.⁺ fraction may berecycled in the hydroisomerization step. Thus, this fraction undergoesisomerisation once again, which means that this cut can be upgraded intolighter products and cold properties can be improved.

In another variation, at least a portion of the 150° C.⁺ cut may berecycled in the hydrotreatment step.

The hydrogen-containing gas which has been separated during theseparation step d) of the process according to the invention and/or theoptional hydroisomerisation step is, if necessary, advantageouslytreated at least in part to reduce its light compound content (C₁ toC₄). Similarly, it advantageously undergoes one or more intermediatepurification treatments, preferably at least one wash with at least oneamine, preferably followed by methanation and/or separation by pressureswing adsorption (PSA) before being recycled.

Advantageously, recycle hydrogen, preferably purified, may be introducedeither with the feed entering the hydrodeoxygenation step according tothe invention and/or into the optional hydroisomerization step, or inthe form of quench hydrogen between the beds of the hydrodeoxygenationcatalysts according to the invention and/or the beds ofhydroisomerization catalysts.

It is also advantageous to supplement the recycle gas with a certainquantity of sulphur-containing compound (such as DMDS,dimethyldisulphide), which produces hydrogen sulphide, H₂S, upon thermaldecomposition. This device can be used if necessary to maintain thecatalyst of the hydrotreatment step and/or the optionalhydroisomerization step (in the case of an active catalyst in thesulphide form) in the sulphurized condition.

EXAMPLE 1 Not in Accordance with the Invention

In example 1, no pre-treatment step is performed.

The feed to be treated is a part refined jatropha oil, thecharacteristics of which are shown in Table 1a.

TABLE 1a Characteristics of the feed to be treated (semi-refinedjatropha oil) Feed treated Jatropha oil Density at 15° C. (kg/m³) 923.5Oxygen (wt %) 11.0 Hydrogen (wt %) 11.4 Sulphur (ppm by weight) 4Nitrogen (ppm by weight) 29 Iodine value (g I2/100 g) 95 Phosphorous(ppm by weight) 52 Magnesium (ppm by weight) 23 Calcium (ppm by weight)35 Sodium (ppm by weight) 8

100 g/h (F=Fo) of this feed was to be treated in a hydrotreatmentreactor constituted by 3 catalytic beds, without a prior pre-treatmentstep.

Each catalytic zone was constituted by one bed of catalyst. The catalystused was identical in the three catalytic zones of the hydrotreatmentstep and comprised 4% by weight of NiO, 21% by weight of MoO₃ and 5% byweight of P₂O₅ supported on a gamma alumina. Said catalyst had a Ni/Moatomic ratio of 0.4.

The supported catalysts were prepared by dry impregnation of the oxideprecursors in solution then sulphurized in situ prior to the test, at atemperature of 350° C., using a straight run gas oil feed supplementedwith 2% by weight of sulphur from dimethyldisulphide (DMDS). After insitu sulphurization in the unit under pressure, the feed from arenewable source constituted by rapeseed oil described in Table 1a wassent to each of the three catalytic zones.

In order to keep the catalyst in the sulphide state, 50 ppm by weight ofsulphur in the form of DMDS was added to the feed. Under the reactionconditions, the DMDS was completely decomposed to form methane and H₂S.

The quantity of recycle liquid used and injected with the unrefined feedonto zone Z1 was 100 g/h (R), which resulted in a total mass recycleratio of 1.0. This recycle was sent in its entirety to the 1^(st)catalytic zone Z1 (R1=R and R2=R3=0).

The total operating pressure was 5 MPa relative. Pure hydrogen was mixedwith each of the flows of the feed, at a flow rate such that at theinlet to each of the catalytic zones, the H₂/unrefined feed ratio was700 Nm³/m³.

Table 1b indicates the flow rates for each of the three feed flows, aswell as the diluent/feed ratio for each of the 3 catalytic zones.

TABLE 1b Operating conditions for the hydrotreatment section/characteristics of the effluent produced Feed flow rate, zone Z1 (F1)(g/h) 9 Feed flow rate, zone Z2 (F2) (g/h) 36.0 Feed flow rate, zone Z3(F3) (g/h) 55.0 Total feed flow rate (F) (g/h) 100.0 Liquid recycle flowrate (R) (g/h) 100.0 Total recycle rate R/F (g/g) 1.0 Local recyclerate, zone Z1 = RF1 (g/g) 11.1 Local recycle rate, zone Z2 = RF2 (g/g)3.0 Local recycle rate, zone Z3 = RF3 (g/g) 2.6 Inlet temperature, zoneZ1 (° C.) 203 Outlet temperature, zone Z3 (° C.) 317 Characteristics ofthe effluent produced Flow rate of hydrocarbons produced (g/h) 86.0Density at 15° C. (kg/m3) 790 Oxygen (wt %) <0.2 Nitrogen (ppm byweight) 5

The experiment was carried out in this case by sending the liquidrecycle to the inlet of the first hydrotreatment catalytic zone Z1,without pre-treatment step. The hydrocarbon produced, upon leaving thehydrotreatment section, had a significant nitrogen content (5 ppm byweight).

Table 1c shows the change with time in the loss of pressure in thehydrotreatment reactor.

TABLE 1c Loss of pressure at t = 0 (bar relative) 0.2 Loss of pressureat t = 250 h (bar relative) 0.5 Loss of pressure at t = 500 h (barrelative) 2.5 Loss of pressure at t = 750 h (bar relative) 8.0 Loss ofpressure at t = 800 h (bar relative) 10.2

The loss of pressure was measured by the difference in the pressurereadings of two gauges arranged at the inlet and the outlet of the bed.

The loss of pressure measured in the hydrotreatment reactor increasedcontinuously during testing until it exceeded a value of 10 bar relativeafter 800 hours, forcing the test to be interrupted at this point. Thisincrease in loss of pressure was due to the accumulation, in thereactor, of metal deposits from the decomposition of the phospholipids.In an industrial-scale unit this phenomenon would lead to a lower cycletime of the hydrotreatment reactor.

The liquid hydrocarbon produced previously was then injected into areactor containing 100 cm³ of a hydroisomerisation catalyst, comprisingNiW/SiO₂Al₂O₃.

The hydrocarbon was injected with a volume flow rate of 100 cm³/g, or aHSV in the hydroisomerisation section of 1.0 h⁻¹.

The hydroisomerisation step was performed on a catalyst fixed bed, usinga pressure of 5 MPa relative and a temperature of 330° C. and a deliveryof pure hydrogen such that the ratio between the volume flow rate ofhydrogen and the volume flow rate of liquid hydrocarbon was 700 N m³/m³.At the gas outlets (C4⁻), a naphtha cut (C5-150° C.), and a kerosene cut(150° C.) were obtained. Table 1d shows the characteristics of thiskerosene cut, which does not meet the specifications of ASTM D7566 interms of the atmospheric distillation end point D86 (end point>300° C.),nor the freezing point (−5° C. for a specified value at −40° C. max).

TABLE 1d Characteristics of the kerosene cut produced Density at 15° C.(kg/m3) 780.1 Starting point D86 (° C.) 160 End point D86 (° C.) 305Nitrogen (ppm by weight) <0.3 Freezing point (° C.) −5 Flash point (°C.) 50

EXAMPLE 2 In Accordance with the Invention

The same feed of semi-refined jatropha oil as in the previous examplewas treated, with an identical feed flow: Fo=F=100 g/h. The catalyst andits preparation were identical to example 1.

The quantity of liquid recycle used, R, was 100 g/h. This recycle wasdivided into a flow RLC containing the paraffinic hydrocarbons fromseparation step d), which was sent in its entirety to the firstcatalytic zone Z1, and the flow rate of which was 80 g/h, and a flow RPPof 20 g/h, which was mixed with the feed flow of rapeseed oil F0. Theratio RPP/F0 was thus 0.2.

The jatropha oil was mixed with the RPP flow in a mixer, and the mixturewas heated to a temperature of 180° C. This mixture was introduced intothe pre-treatment zone, in which said mixture flowed through 70 cm³ of afixed bed of spherical alumina having a void fraction of 0.46 with adiameter of between 3 and 6 mm. The alumina had a macroporous volume,measured by mercury intrusion, that is to say a volume of pores whoseaverage diameter was 500 A, equal to 0.35 ml/g, a total porous volume of1.2 ml/g and a specific surface expressed in S_(BET) of 140 m²/g.

At the end of this pre-treatment step, the perfect separation wasperformed of a flow F of pre-treated oil, and the flow RPP containingthe paraffinic hydrocarbons. Thus ε=0. This flow RPP was mixed with therecycle flow RLC sent to the 1^(st) catalytic zone in accordance withconfiguration (ii) of the process flowsheet.

At the end of the pre-treatment, the characteristics identified of theoil flow F were as shown in Table 2a.

TABLE 2a Characteristics of the pre-treated feed (jatropha oil) - Flow FFeed treated Jatropha oil Density at 15° C. (kg/m³) 923.5 Oxygen (wt %)11.0 Hydrogen (wt %) 11.4 Sulphur (ppm by weight) 3 Nitrogen (ppm byweight) 13 Phosphorous (ppm by weight) <1 Calcium (ppm by weight) <1Magnesium (ppm by weight) <1 Sodium (ppm by weight) <1

The pre-treatment allows simultaneous elimination of the phosphorous andthe main elements present in the oil (calcium, magnesium and sodium).This step also allows a significant reduction in the nitrogen content ofthe starting oil, due to the elimination of certain nitrogen compounds(13 ppm instead of 29 ppm initially).

The operating conditions of the hydrotreatment section were identical tothose used in example 1.

The total mass recycle rate RT=(RLC+RPP)/F=R/F (configuration (ii)), wasidentical to example 1 and equal to 1.0,

The distribution of the feed across the various catalytic hydrotreatmentzones was identical to that adopted in example 1. Table 2b shows thevarious flow rates and in particular of each of the three flowssupplying the catalytic hydrotreatment zones, and the diluant/feedratios for each of the 3 catalytic zones.

TABLE 2b Operating conditions of the hydrotreatment sections andcharacteristics of the effluent produced Feed flow rate, zone Z1 (F1)(g/h) 9.0 Feed flow rate, zone Z2 (F2) (g/h) 36.0 Feed flow rate, zoneZ3 (F3) (g/h) 55.0 Total feed flow rate (F) (g/h) 100.0 Liquid recycleflow rate (RLC) (g/h) 80.0 Liquid recycle flow rate (RPP) (g/h) 20.0Total liquid recycle flow rate (R) (g/h) 100.0 Ratio RPP/Fo (g/g) 0.2Ratio RPP/R (g/g) 0.2 Total liquid recycle rate RT (=R/F) (g/g) 1.0Diluent/feed ratio, zone Z1 = (g/g) 11.1 Diluent/feed ratio, zone Z2 =(g/g) 3.0 Diluent/feed ratio, zone Z3 = (g/g) 2.6 Inlet temperature,zone Z1 (° C.) 203 Outlet temperature, zone Z3 (° C.) 317Characteristics of the effluent produced Flow rate of hydrocarbonsproduced (g/h) 86.0 Density at 15° C. (kg/m3) 790 Oxygen (wt %) <0.2Nitrogen (ppm by weight) <0.3

Compared with example 1, the pre-treatment section allows a verysignificant drop in the nitrogen content of the oil flow supplying thehydrotreatment section, and allows a flow of hydrocarbons to be obtainedat the outlet that is free from oxygen and nitrogen (nitrogen content ofless than the detection limit, or less than 0.3 ppm by weight).

Table 2c shows the change with time in the loss of pressure in thehydrotreatment section.

TABLE 2c Change with time of the loss of pressure in the hydrotreatmentreactor Loss of pressure at t = 0 (bar relative) 0.3 Loss of pressure att = 250 h (bar relative) 0.4 Loss of pressure at t = 500 h (barrelative) 0.4 Loss of pressure at t = 750 h (bar relative) 0.4 Loss ofpressure at t = 800 h (bar relative) 0.4

The loss of pressure was measured in the same way as for example 1.

During the 800 hours during which the hydrotreatment test was running,no significant increase in the loss of pressure in the reactor wasobserved. This was due to the fact that the flow of oil supplying thereactor was free from metals, thereby eliminating the progressiveclogging of the reactor through the accumulation of solid metaldeposits.

This hydrocarbon was then treated in a hydroisomerisation reactor andunder operating conditions that were strictly identical to thosedescribed in example 1. At the gas outlet (C4⁻), a naphtha cut (C5-150°C.), and a kerosene cut (150° C.⁺) were then obtained.

Table 2d shows the characteristics of the kerosene cut produced underthese conditions.

TABLE 2d Characteristics of the kerosene cut produced Density at 15° C.(kg/m3) 764.5 Starting point D86 (° C.) 160 End point 86 (° C.) 295Nitrogen (ppm by weight) <0.3 Freezing point (° C.) −50 Flash point (°C.) 50

It can be seen that the freezing point of the kerosene cut producedaccording to the present invention meets the ASTM D7566 specificationsrequiring a freezing point of −40° C. max.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The preceding preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the disclosure in any way whatsoever.

The entire disclosures of all applications, patents and publications,cited herein and of corresponding French application No. 11/03411, filedNov. 8, 2011, are incorporated by reference herein.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

The invention claimed is:
 1. A process for the hydrotreatment of a feedoriginating from renewable sources in order to produce paraffinichydrocarbons comprising: a) mixing a total feed flow F0 with a flow RPPcomprising at least a portion of a liquid fraction R containingparaffinic hydrocarbons from the separation d), said mixture beingheated to a temperature of between 130 and 320° C.; b) introducing saidmixture into a pre-treatment zone in which flow of said mixture takesplace via a porous medium comprising a fixed particle bed , said fixedbed having a void fraction of between 0.25 and 0.8; c) hydrotreatingeffluent from the pretreatment zone in the presence of hydrogen inexcess of theoretical hydrogen consumption and under hydrotreatmentconditions in a fixed bed reactor having a plurality of catalytic zonesdisposed in series and comprising a hydrotreatment catalyst, by dividingeffluent resulting from the pre-treatment zone (F+εRPP), ε being between0 and 1, into at least a certain number of different part flows(F1+ε₁RPP) to (Fn+ε_(n)RPP) equal to the number of catalytic zones n ina fixed bed reactor, injecting a first part flow (F1+ε₁RPP) into a firstcatalytic zone, injecting a second part flow (F2+ε₂RPP) into the secondcatalytic zone and so on, if n greater than 2, the sum of the ε_(i)being equal to ε; the various part flows are injected into successivecatalytic zones in increasing proportions such that F1/F is less than orequal to F2/F, which itself is less than or equal to F3/F and so onuntil F(n-1)/F is less than or equal to Fn/F, in order to produce aneffluent containing paraffinic hydrocarbons; d) subjecting said effluentcontaining paraffinic hydrocarbons to at least one separation allowingseparation of at least one gaseous fraction and at least one liquidfraction containing the paraffinic hydrocarbons; e) dividing at least aportion R of said liquid fraction containing the paraffinic hydrocarbonsfrom b) mixing RPP into at least a flow RLC and into said recycle flowRPP upstream of a) and with the total feed flow F0, dividing said flowRLC into at least a certain number of different part flows R1-Rn lessthan or equal to the number of catalytic zones n in the reactor, saidflows R1-Rn being recycled upstream of the catalytic zones 1-n, the flowof paraffinic hydrocarbons (R1+ε₁RPP) sent to the first catalytic zoneand the part flow F1 of the feed introduced into the first catalyticzone having a weight ratio greater than or equal to
 10. 2. The processaccording to claim 1 in which said feed originating from renewablesources is oils or fats of vegetable or animal origin or mixturesthereof, containing triglycerides and/or free fatty acids and/or esters.3. The process according to claim 1 wherein the flow RPP introduced ina) in relation to the flow of total fresh feed F0 has a mass flow ratioRPP/F0 between 0.1 and
 5. 4. The process according to claim 3 in whichthe mass flow ratio RPP/F0 is between 0.5 and
 3. 5. The processaccording to claim 1 in which catalyst particles in the fixed bed arematerials with a specific surface of between 0.5 and 320m²/g.
 6. Theprocess according to claim 5 in which said particles are porousrefractory oxides, oxide ceramics, non-oxide ceramics, compositeceramics, silicon carbides, activated carbons, calcium aluminates,metals or graphite.
 7. The process according to claim 6 in which saidparticles are porous refractory oxides that are alumina, silica,activated alumina, silica-aluminas, metal oxides or non-metal oxides. 8.The process according to claim 1 in which the effluent from thepre-treatment zone (F+εRPP) is introduced into a separation zone inorder to separate a paraffin-rich effluent (1-ε) RPP.
 9. The processaccording to claim 1 having a in which the total recycle rate (RT)lessthan 1.0.
 10. The process according to claim 1 wherein the flow RPP isintroduced into a) in relation to the total recycle flow R at a massflow RPP/R ratio between 0.1 and 0.9.
 11. The process according to claim1 in which said feed originating from renewable sources is treated in amixture with oil cuts that are gas oils, kerosenes or gasolines from oilrefining processes.
 12. The process according to claim 1 in which atleast a portion of the liquid fraction containing the paraffinichydrocarbons from separation d) not recycled is hydroisomerized in thepresence of a hydroisomerization catalyst.